Ingrosso D, Fowler A V, Bleibaum J, Clarke S
Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569.
Biochem Biophys Res Commun. 1989 Aug 15;162(3):1528-34. doi: 10.1016/0006-291x(89)90848-6.
Endoproteinase Asp-N, a metalloprotease from a mutant strain of Pseudomonas fragi, has been reported to specifically cleave on the N-terminal side of aspartyl and cysteic acid residues. We utilized this enzyme to generate fragments for determining the amino acid sequence of the D-aspartyl/L-isoaspartyl methyltransferase isozyme I from human erythrocytes. Surprisingly, we identified cleavage sites for this enzyme at the N-terminal side of several glutamyl residues in addition to the expected cleavage sites at aspartyl residues. The ability of this enzyme to cleave polypeptides at both glutamyl and aspartyl residues was confirmed by mapping additional sites on erythrocyte carbonic anhydrase I. These results indicate that a more appropriate name for this enzyme may be Endoproteinase Asp/Glu-N.
天冬氨酸特异性内肽酶（Endoproteinase Asp-N）是一种来自脆弱拟杆菌突变株的金属蛋白酶，据报道它能特异性地在天冬氨酸和半胱磺酸残基的N端进行切割。我们利用这种酶来生成片段，以确定人红细胞中天冬氨酸/D-异天冬氨酸甲基转移酶同工酶I的氨基酸序列。令人惊讶的是，除了在天冬氨酸残基处的预期切割位点外，我们还在几个谷氨酰胺残基的N端确定了该酶的切割位点。通过在红细胞碳酸酐酶I上定位其他位点，证实了该酶在谷氨酰胺和天冬氨酸残基处切割多肽的能力。这些结果表明，这种酶更合适的名称可能是天冬氨酸/谷氨酰胺特异性内肽酶（Endoproteinase Asp/Glu-N）。
